Enhancement of CO2 adsorption on polybenzoxazine-modified activated carbon

Abstract

CO2 adsorption on the palm shell-based activated carbon (PSAC), coconut shell-based activated carbon (CSAC), and polybenzoxazine (PBZ) grafted CSAC was investigated. The PBZ loading was varied by different benzoxazine monomer (BZ) solution concentrations from 1.0 to 5.0 g/L. The solvents that used for BZ impregnation onto adsorbents were methanol and chloroform. CO2 adsorption isotherms were investigated at 30, 50, and 75 °C. Adsorbents were characterized by TG-DTA, FTIR, SEM, and surface area and pore size analysis. The results showed that the CSAC had higher CO2 adsorption capacity than the PSAC, and methanol was a good solvent for the impregnation. The 0.27 wt.% PBZ grafted CSAC improved the CO2 adsorption capacity at 50 and 75 °C because the chemisorption was preferred at these high temperatures. A decrease in the adsorption capacity was found when the CSAC was loaded with 0.92 wt.% PBZ or higher because of the pore filling effect. An optimum amount of PBZ loading is needed to increase the CO2 adsorption capacity. The used adsorbents were regenerated at 120 °C to desorb CO2 from the adsorbent. The CO2 adsorption capacity of the regenerated adsorbents had minimal loss in the capacity.